Computational modeling offers new insight into Drosophila germ granule development.

The packaging of specific mRNAs into ribonucleoprotein granules called germ granules is required for germline proliferation and maintenance. During Drosophila germ granule development, mRNAs such as nanos (nos) and polar granule component (pgc) localize to germ granules through a stochastic seeding and self-recruitment process that generates homotypic clusters: aggregates containing multiple copies of a specific transcript. Germ granules vary in mRNA composition with respect to the different transcripts that they contain and their quantity. However, what influences germ granule mRNA composition during development is unclear. To gain insight into how germ granule mRNA heterogeneity arises, we created a computational model that simulates granule development. Although the model includes known mechanisms that were converted into mathematical representations, additional unreported mechanisms proved to be essential for modeling germ granule formation. The model was validated by predicting defects caused by changes in mRNA and protein abundance. Broader application of the model was demonstrated by quantifying nos and pgc localization efficacies and the contribution that an element within the nos 3' untranslated region has on clustering. For the first time, a mathematical representation of Drosophila germ granule formation is described, offering quantitative insight into how mRNA compositions arise while providing a new tool for guiding future studies.

Exploring Predictors of Response to Dacomitinib in EGFR-Amplified Recurrent Glioblastoma.

PURPOSE: Despite the high frequency of EGFR genetic alterations in glioblastoma (GBM), EGFR-targeted therapies have not had success in this disease. To improve the likelihood of efficacy, we targeted adult patients with recurrent GBM enriched for EGFR gene amplification, which occurs in approximately half of GBM, with dacomitinib, a second-generation, irreversible epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor that penetrates the blood-brain barrier, in a multicenter phase II trial. PATIENTS AND METHODS: We retrospectively explored whether previously described EGFR extracellular domain (ECD)-sensitizing mutations in the context of EGFR gene amplification could predict response to dacomitinib, and in a predefined subset of patients, we measured post-treatment intratumoral dacomitinib levels to verify tumor penetration. RESULTS: We found that dacomitinib effectively penetrates contrast-enhancing GBM tumors. Among all 56 treated patients, 8 (14.3%) had a clinical benefit as defined by a duration of treatment of at least 6 months, of whom 5 (8.9%) remained progression free for at least 1 year. Presence of EGFRvIII or EGFR ECD missense mutation was not associated with clinical benefit. We evaluated the pretreatment transcriptome in circulating extracellular vesicles (EVs) by RNA sequencing in a subset of patients and identified a signature that distinguished patients who had durable benefit versus those with rapid progression. CONCLUSION: While dacomitinib was not effective in most patients with EGFR-amplified GBM, a subset experienced a durable, clinically meaningful benefit. Moreover, EGFRvIII and EGFR ECD mutation status in archival tumors did not predict clinical benefit. RNA signatures in circulating EVs may warrant investigation as biomarkers of dacomitinib efficacy in GBM.

Transferable vancomycin resistance in clade B commensal-type Enterococcus faecium.

Objectives: Vancomycin-resistant Enterococcus faecium is a leading cause of MDR hospital infection. Two genetically definable populations of E. faecium have been identified: hospital-adapted MDR isolates (clade A) and vancomycin-susceptible commensal strains (clade B). VanN-type vancomycin resistance was identified in two isolates of E. faecium recovered from blood and faeces of an immunocompromised patient. To understand the genomic context in which VanN occurred in the hospitalized patient, the risk it posed for transmission in the hospital and its origins, it was of interest to determine where these strains placed within the E. faecium population structure. Methods: We obtained the genome sequence of the VanN isolates and performed comparative and functional genomics of the chromosome and plasmid content. Results: We show that, in these strains, VanN occurs in a genetic background that clusters with clade B E. faecium, which is highly unusual. We characterized the chromosome and the conjugative plasmid that carries VanN resistance in these strains, pUV24. This plasmid exhibits signatures of in-host selection on the vanN operon regulatory system, which are associated with a constitutive expression of vancomycin resistance. VanN resistance in clade B strains may go undetected by current methods. Conclusions: We report a case of vancomycin resistance in a commensal lineage of E. faecium responsible for an atypical bacteraemia in an immunocompromised patient. A reservoir of transferable glycopeptide resistance in the community could pose a concern for public health.

Opioid overdose education and naloxone distribution: Development of the Veterans Health Administration's national program.

OBJECTIVES: To prevent opioid-related mortality, the Veterans Health Administration (VHA) developed a national Opioid Overdose Education and Naloxone Distribution (OEND) program. SETTING: VHA's OEND program sought national implementation of OEND across all medical facilities (n = 142). PRACTICE DESCRIPTION: This paper describes VHA's efforts to facilitate nationwide health care system-based OEND implementation, including the critical roles of VHA's national pharmacy services and academic detailing services. PRACTICE INNOVATION: VHA is the first large health care system in the United States to implement OEND nationwide. Launching the national program required VHA to translate a primarily community-based public health approach to OEND into a health care system-based approach that distributed naloxone to patients with opioid use disorders as well as to patients prescribed opioid analgesics. Key innovations included developing steps to implement OEND, pharmacy developing standard naloxone rescue kits, adding those kits to the VHA National Formulary, centralizing kit distribution, developing clinical guidance for issuing naloxone kits, and supporting OEND as a focal campaign of academic detailing. Other innovations included the development of patient and provider education resources (e.g., brochures, videos, accredited training) and implementation and evaluation resources (e.g., technical assistance, clinical decision support tools). EVALUATION: Clinical decision support tools that leverage VHA national data are available to clinical staff with appropriate permissions. These tools allow staff and leaders to evaluate OEND implementation and provide actionable next steps to help them identify patients who could benefit from OEND. RESULTS: Through fiscal year 2016, VHA dispensed 45,178 naloxone prescriptions written by 5693 prescribers to 39,328 patients who were primarily prescribed opioids or had opioid use disorder. As of February 2, 2016, there were 172 spontaneously reported opioid overdose reversals with the use of VHA naloxone prescriptions. CONCLUSION: VHA has successfully translated community-based OEND into health care system-based OEND targeting 2 patient populations. There is a tremendous amount that can be learned from VHA's experience implementing this novel health care innovation nationwide.

Flecainide Toxicity: A Case Report and Systematic Review of its Electrocardiographic Patterns and Management.

In the setting of flecainide toxicity, supraventricular tachycardia can manifest as a bizarre right or left bundle branch block, sometimes with a northwest axis, and can easily be mistaken for ventricular tachycardia leading to inappropriate therapy. We conducted a comprehensive literature review for cases of flecainide toxicity. We found 21 articles of flecainide toxicity in adult patients in which 22 ECG tracings were published. In patients with flecainide toxicity and QRS duration ≤ 200 ms, the ECGs were more likely to show RBBB, visible P waves (p = 0.03), and shorter QT (p = 0.02) and QTc intervals (p = 0.004). With QRS duration > 200 ms, the ECGs were more likely to show LBBB, loss of P waves, a northwest axis (p = 0.01), and longer QT and QTc intervals. Deaths were reported only in patients with QRS duration >200 ms, and the outcome of death or requirement for mechanical circulatory support was more prevalent in patients with a QRS duration > 200 ms [2/13 (15.4 %) vs. 6/10 (60 %), p = 0.04]. In patients with access to the medication, flecainide toxicity should be suspected with: (1) broad QRS, (2) RBBB morphology with QRS ≤ 200 ms; RBBB or LBBB morphology with QRS ≥ 200 ms (3) HR out of proportion to the degree of hemodynamic instability. The duration of the QRS interval is prognostic, with mortality and the requirement for mechanical circulatory support being more common in patients with a QRS > 200 ms.

Giant left atrial appendage aneurysm: A case of mistaken identity.

Left atrial appendage (LAA) aneurysm is a rare condition that can be congenital or acquired. Most cases are discovered incidentally. However, the most frequent clinical presentations include supraventricular tachycardias and systemic embolization. Most cases in the literature were treated by resection of the LAA, and it has been recommended to perform LAA resection even in asymptomatic patients in order to prevent thromboembolic events. Here, we describe the safe, conservative management of a patient who was initially felt to have congenital partial absence of the left pericardium but at surgery the diagnosis of LAA aneurysm was established. .

Impact of the 2013 American College of Cardiology/American Heart Association cholesterol guidelines on the prescription of high-intensity statins in patients hospitalized for acute coronary syndrome or stroke.

BACKGROUND: The 2013 American College of Cardiology/American Heart Association cholesterol management guidelines represented a paradigm shift from the National Cholesterol Education Program Adult Treatment Panel III guidelines, replacing low-density lipoprotein cholesterol targets with a risk assessment model to guide statin therapy. Our objectives are to compare provider prescription of high-intensity statin therapy in patients hospitalized with acute coronary syndrome (ACS) or cerebrovascular accident (CVA) before and after the publication of the 2013 cholesterol guidelines, determine potential predictors of high-intensity statin utilization, and identify targets for improvement in cardiovascular risk reduction among these high-risk populations. METHODS: A single-center retrospective cohort study of 695 patients discharged with a diagnosis of ACS or CVA in the 6months before (n=359) and after (n=336) the release of the 2013 American College of Cardiology/American Heart Association cholesterol guidelines. Patient characteristics were compared using analysis of variance and χ2 tests. Multivariable logistic regression models were used to assess clinical predictors of provider utilization of high-intensity statins. RESULTS: After the 2013 cholesterol guidelines, the rate of prescribing high-intensity statins was greater for statin-naïve patients compared with those already on statin therapy (odds ratio [OR]0.51, P=.02). Prescription of high-intensity statins was higher for patients with ACS compared with CVA (OR 8.4, P<.001-pre-2013 guidelines; OR 4.5, P<.001-post-2013 guidelines). Prescription of high-intensity statins steadily improved over the study period, significantly among patients with CVA (P<.001). CONCLUSIONS: Physicians were more likely to prescribe high-intensity statins in statin-naïve patients as compared with intensifying existing statin therapy, and their prescription pattern was lower after CVA vs ACS.

Pharmacy Benefits Management in the Veterans Health Administration Revisited: A Decade of Advancements, 2004-2014.

Over the past decade, the Department of Veterans Affairs (VA) Pharmacy Benefits Management Services (PBM) has enhanced its formulary management activities and added programs to ensure that the national drug plan continues to meet the pharmacy needs of veterans and to promote safe and appropriate drug therapy in the face of rising medication expenditures. This article describes the broad range of services provided by the VA PBM that work in partnership to deliver a high-quality and sustainable pharmacy benefit for veterans. In support of formulary management, VA PBM pharmacists prepare extensive clinical guidance documents (e.g., drug monographs and criteria for use) that are used by physicians and pharmacists with operational and clinical oversight of the VA national formulary. The VA PBM has utilized various contracting techniques and continually evaluates drug utilization data to identify opportunities for potential savings. Remarkably, since before 2004, the average acquisition cost for a 1-month supply of medication has remained fairly stable at approximately $13-$15. Two new VA PBM programs are the VA Center for Medication Safety (VA MedSAFE) and the Clinical Pharmacy Practice Office (CPPO). VA MedSAFE is a comprehensive pharmacovigilance program focused on the detection, assessment, and prevention of adverse drug events, and CPPO is dedicated to improving safe and appropriate medication use by supporting and expanding clinical pharmacy practice. Moving forward, the VA PBM will consider new initiatives to stay at the forefront of providing quality care while maintaining economic viability. DISCLOSURES: No outside funding supported this research. This work was supported by VA Pharmacy Benefits Management Services (VA PBM), Hines, Illinois, and VA Pittsburgh Healthcare System, Pittsburgh, Pennsylvania. Glassman is co-director of the VA Center for Medication Safety, which is part of the VA PBM. He is also part of the Medical Advisory Panel for the VA PMB. All other authors are employed by the VA PBM. The views expressed in this article are those of the authors, and no official endorsement by the U.S. Department of Veteran Affairs or the U.S. government is intended or should be inferred. Study concept and design were contributed by Valentino, Cunningham, Good, Aspinall, and Sales. Calabrese and Ourth took the lead in data collection, along with Good, Cunningham, Aspinall, Sales, Burk, Moore, Neuhauser, and Golterman. Data interpretation was performed by Burk, Newhauser, and Golterman, along with Glassman, Calabrese, Moore, and Ourth. The manuscript was written by Aspinall and Sales, along with Burk, Newhauser, Golterman, Ourth, and Cunningham. Good, Glassman, and Moore revised the manuscript, along with Calabrese, Valentino, and Aspinall.

Changes in the preferences of US physicians-in-training for medical interventions throughout medical education.

CONTEXT: There exists a disparity between the views of physicians and the views of their patients on end-of-life decisions. However, the timing of when the end-of-life preferences of physicians and non-medically-trained individuals diverge is currently unknown. The objective of this paper is to characterise how preferences for medical interventions change throughout medical education and residency or fellowship training when confronted with scenarios of critical or terminal illness. METHODS: This is a single-centre cross-sectional study that enrolled medical students at Sidney Kimmel Medical College and residents and fellows at Thomas Jefferson University Hospital. Through an online survey we determined the preferences of medical trainees for specific interventions throughout medical training when presented with different clinical scenarios. Interventions were organised into three categories: standard, intermediate and aggressive. We analysed responses to questions regarding different scenarios in separate repeated measures logistic regression models. The probability of declining medical interventions was modelled, and significant predictors of refusal of interventions were identified. RESULTS: Years of training was a significant predictor of declining interventions for several scenarios. When faced with permanent physical disability, increased years of training led to a higher rate of refusal of intermediate (OR = 1.14 [1.02-1.28], p = 0.02) and aggressive interventions (OR = 1.15 [1.03-1.28], p = 0.01). For the scenario of terminal illness with associated physical disability, years of training significantly influenced refusal of intermediate (OR = 1.14 [1.04-1.26], p = 0.006) and aggressive (OR = 1.20 [1.08-1.34], p = 0.001) interventions. For the scenario of permanent cognitive impairment, increased years of training led to a higher rate of refusal of standard (OR = 1.14 [1.01-1.29], p = 0.03), intermediate (OR = 1.30 [1.13-1.50], p < 0.001) and aggressive (OR = 1.38 [1.14-1.66], p = 0.001) interventions. CONCLUSION: Changes in end-of-life preferences occur throughout medical training. Years of training influenced the likelihood of declining medical interventions when faced with scenarios of terminal illness and physical or cognitive disability.

Bacterial Hypoxic Responses Revealed as Critical Determinants of the Host-Pathogen Outcome by TnSeq Analysis of Staphylococcus aureus Invasive Infection.

Staphylococcus aureus is capable of infecting nearly every organ in the human body. In order to infiltrate and thrive in such diverse host tissues, staphylococci must possess remarkable flexibility in both metabolic and virulence programs. To investigate the genetic requirements for bacterial survival during invasive infection, we performed a transposon sequencing (TnSeq) analysis of S. aureus during experimental osteomyelitis. TnSeq identified 65 genes essential for staphylococcal survival in infected bone and an additional 148 mutants with compromised fitness in vivo. Among the loci essential for in vivo survival was SrrAB, a staphylococcal two-component system previously reported to coordinate hypoxic and nitrosative stress responses in vitro. Healthy bone is intrinsically hypoxic, and intravital oxygen monitoring revealed further decreases in skeletal oxygen concentrations upon S. aureus infection. The fitness of an srrAB mutant during osteomyelitis was significantly increased by depletion of neutrophils, suggesting that neutrophils impose hypoxic and/or nitrosative stresses on invading bacteria. To more globally evaluate staphylococcal responses to changing oxygenation, we examined quorum sensing and virulence factor production in staphylococci grown under aerobic or hypoxic conditions. Hypoxic growth resulted in a profound increase in quorum sensing-dependent toxin production, and a concomitant increase in cytotoxicity toward mammalian cells. Moreover, aerobic growth limited quorum sensing and cytotoxicity in an SrrAB-dependent manner, suggesting a mechanism by which S. aureus modulates quorum sensing and toxin production in response to environmental oxygenation. Collectively, our results demonstrate that bacterial hypoxic responses are key determinants of the staphylococcal-host interaction.

Bilhemia: A Rare Complication of Transjugular Intraheptic Portosytemic Shunt.

A 56-year-old woman with cirrhosis due to chronic hepatitis C underwent emergent transjugular intrahepatic portosystemic shunt (TIPS) due to a ruptured esophageal varix during esophagogastroduodenoscopy. Following TIPS, the patient experienced a rapid rise in serum bilirubin with no evidence of biliary obstruction or hepatic injury. She was determined to have bilhemia, a rare but serious complication of TIPS.

Mutations in pneumococcal cpsE generated via in vitro serial passaging reveal a potential mechanism of reduced encapsulation utilized by a conjunctival isolate.

UNLABELLED: The polysaccharide capsule of Streptococcus pneumoniae is required for nasopharyngeal colonization and for invasive disease in the lungs, blood, and meninges. In contrast, the vast majority of conjunctival isolates are acapsular. The first serotype-specific gene in the capsule operon, cpsE, encodes the initiating glycosyltransferase and is one of the few serotype-specific genes that can tolerate null mutations. This report characterizes a spontaneously arising TIGR4 mutant exhibiting a reduced capsule, caused by a 6-nucleotide duplication in cpsE which results in duplication of Ala and Ile at positions 45 and 46. This strain (AI45dup) possessed more exposed phosphorylcholine and was hypersusceptible to C3 complement deposition compared to the wild type. Accordingly, the mutant was significantly better at forming abiotic biofilms and binding epithelial cells in vitro but was avirulent in a sepsis model. In vitro serial passaging of the wild-type strain failed to reproduce the AI45dup mutation but instead led to a variety of mutants with reduced capsule harboring single nucleotide polymorphisms (SNPs) in cpsE. A single passage in the sepsis model after high-dose inoculation readily yielded revertants of AI45dup with restored wild-type capsule level, but the majority of SNP alleles of cpsE could not revert, suppress, or bypass. Analysis of cpsE in conjunctival isolates revealed a strain with a single missense mutation at amino acid position 377, which was responsible for reduced encapsulation. This study supports the hypothesis that spontaneous, nonreverting mutations in cpsE serve as a form of adaptive mutation by providing a selective advantage to S. pneumoniae in niches where expression of capsule is detrimental. IMPORTANCE: While the capsule of Streptococcus pneumoniae is required for colonization and invasive disease, most conjunctival isolates are acapsular by virtue of deletion of the entire capsular operon. We show that spontaneous acapsular mutants isolated in vitro harbor mostly nonrevertible single nucleotide polymorphism (SNP) null mutations in cpsE, encoding the initiating glycosyltransferase. From a small collection of acapsular conjunctival isolates, we identified one strain with a complete capsular operon but containing a SNP in cpsE that we show is responsible for the acapsular phenotype. We propose that acapsular conjunctival isolates may arise initially from such nonreverting SNP null mutations in cpsE, which can be followed later by deletion of portions or all of the cps operon.

Unencapsulated Streptococcus pneumoniae from conjunctivitis encode variant traits and belong to a distinct phylogenetic cluster.

Streptococcus pneumoniae, an inhabitant of the upper respiratory mucosa, causes respiratory and invasive infections as well as conjunctivitis. Strains that lack the capsule, a main virulence factor and the target of current vaccines, are often isolated from conjunctivitis cases. Here we perform a comparative genomic analysis of 271 strains of conjunctivitis-causing S. pneumoniae from 72 postal codes in the United States. We find that the vast majority of conjunctivitis strains are members of a distinct cluster of closely related unencapsulated strains. These strains possess divergent forms of pneumococcal virulence factors (such as CbpA and neuraminidases) that are not shared with other unencapsulated nasopharyngeal S. pneumoniae. They also possess putative adhesins that have not been described in encapsulated pneumococci. These findings suggest that the unencapsulated strains capable of causing conjunctivitis utilize a pathogenesis strategy substantially different from that described for S. pneumoniae at other infection sites.

Genes contributing to Staphylococcus aureus fitness in abscess- and infection-related ecologies.

UNLABELLED: Staphylococcus aureus is a leading cause of both community- and hospital-acquired infections that are increasingly antibiotic resistant. The emergence of S. aureus resistance to even last-line antibiotics heightens the need for the development of new drugs with novel targets. We generated a highly saturated transposon insertion mutant library in the genome of S. aureus and used Tn-seq analysis to probe the entire genome, with unprecedented resolution and sensitivity, for genes of importance in infection. We further identified genes contributing to fitness in various infected compartments (blood and ocular fluids) and compared them to genes required for growth in rich medium. This resulted in the identification of 426 genes that were important for S. aureus fitness during growth in infection models, including 71 genes that could be considered essential for survival specifically during infection. These findings highlight novel as well as previously known genes encoding virulence traits and metabolic pathways important for S. aureus proliferation at sites of infection, which may represent new therapeutic targets. IMPORTANCE: Staphylococcus aureus continues to be a leading cause of antibiotic-resistant community and nosocomial infection. With the bacterium's acquisition of resistance to methicillin and, more recently, vancomycin, the need for the development of new drugs with novel targets is urgent. Applying a highly saturated Tn-seq mutant library to analyze fitness and growth requirements in a murine abscess and in various infection-relevant fluids, we identified S. aureus traits that enable it to survive and proliferate during infection. This identifies potential new targeting opportunities for the development of novel therapeutics.

High-Quality Draft Genome Sequence of Vagococcus lutrae Strain LBD1, Isolated from the Largemouth Bass Micropterus salmoides.

Vagococci are usually isolated from marine hosts and occasionally from endodontic infections. Using 16S rRNA gene comparison, the closest relatives are members of the genera Enterococcus and Carnobacterium. A draft sequence of Vagococcus lutrae was generated to clarify the relationship of Vagococcus to these and other related low-G+C Gram-positive bacteria.

Mechanisms of Weight Regain following Weight Loss.

Obesity is a world-wide pandemic and its incidence is on the rise along with associated comorbidities. Currently, there are few effective therapies to combat obesity. The use of lifestyle modification therapy, namely, improvements in diet and exercise, is preferable over bariatric surgery or pharmacotherapy due to surgical risks and issues with drug efficacy and safety. Although they are initially successful in producing weight loss, such lifestyle intervention strategies are generally unsuccessful in achieving long-term weight maintenance, with the vast majority of obese patients regaining their lost weight during followup. Recently, various compensatory mechanisms have been elucidated by which the body may oppose new weight loss, and this compensation may result in weight regain back to the obese baseline. The present review summarizes the available evidence on these compensatory mechanisms, with a focus on weight loss-induced changes in energy expenditure, neuroendocrine pathways, nutrient metabolism, and gut physiology. These findings have added a major focus to the field of antiobesity research. In addition to investigating pathways that induce weight loss, the present work also focuses on pathways that may instead prevent weight regain. Such strategies will be necessary for improving long-term weight loss maintenance and outcomes for patients who struggle with obesity.

Obesity pharmacotherapy: what is next?

The increase in obesity in the Unites States and around the world in the last decade is overwhelming. The number of overweight adults in the world surpassed 1 billion in 2008. Health hazards associated with obesity are serious and include heart disease, sleep apnea, diabetes, and cancer. Although lifestyle modifications are the most straightforward way to control weight, a large portion of the population may not be able to rely on this modality alone. Thus, the development of anti-obesity therapeutics represents a major unmet medical need. Historically, anti-obesity pharmacotherapies have been unsafe and minimally efficacious. A better understanding of the biology of appetite and metabolism provides an opportunity to develop drugs that may offer safer and more effective alternatives for weight management. This review discusses drugs that are currently on the market and in development as anti-obesity therapeutics based on their target and mechanism of action. It should serve as a roadmap to establish expectations for the near future for anti-obesity drug development.

GUCY2C opposes systemic genotoxic tumorigenesis by regulating AKT-dependent intestinal barrier integrity.

The barrier separating mucosal and systemic compartments comprises epithelial cells, annealed by tight junctions, limiting permeability. GUCY2C recently emerged as an intestinal tumor suppressor coordinating AKT1-dependent crypt-villus homeostasis. Here, the contribution of GUCY2C to barrier integrity opposing colitis and systemic tumorigenesis is defined. Mice deficient in GUCY2C (Gucy2c(-/-)) exhibited barrier hyperpermeability associated with reduced junctional proteins. Conversely, activation of GUCY2C in mice reduced barrier permeability associated with increased junctional proteins. Further, silencing GUCY2C exacerbated, while activation reduced, chemical barrier disruption and colitis. Moreover, eliminating GUCY2C amplified, while activation reduced, systemic oxidative DNA damage. This genotoxicity was associated with increased spontaneous and carcinogen-induced systemic tumorigenesis in Gucy2c(-/-) mice. GUCY2C regulated barrier integrity by repressing AKT1, associated with increased junction proteins occludin and claudin 4 in mice and Caco2 cells in vitro. Thus, GUCY2C defends the intestinal barrier, opposing colitis and systemic genotoxicity and tumorigenesis. The therapeutic potential of this observation is underscored by the emerging clinical development of oral GUCY2C ligands, which can be used for chemoprophylaxis in inflammatory bowel disease and cancer.

A broadly applicable approach to T cell epitope identification: application to improving tumor associated epitopes and identifying epitopes in complex pathogens.

Epitopes are a hallmark of the antigen specific immune response. The identification and characterization of epitopes is essential for modern immunologic studies, from investigating cellular responses against tumors to understanding host/pathogen interactions especially in the case of bacteria with intracellular residence. Here, we have utilized a novel approach to identify T cell epitopes exploiting the exquisite ability of particulate antigens, in the form of beads, to deliver exogenous antigen to both MHC class I and class II pathways for presentation to T cell hybridomas. In the current study, we coupled this functional assay with two distinct protein expression libraries to develop a methodology for the characterization of T cell epitopes. One set of expression libraries containing single amino acid substitutions in a defined epitope sequence was interrogated to identify epitopes with enhanced T cell stimulation for a MHC class I epitope. The second expression library is comprised of the majority of open reading frames from the intracellular pathogen and potential biowarfare agent, Francisella tularensis. By automating aspects of this technology, we have been able to functionally screen and identify novel T cell epitopes within F. tularensis. We have also expanded upon these studies to generate a novel expression vector that enables immunization of recombinant protein into mice, which has been utilized to facilitate T cell epitope discovery for proteins that are critically linked to Francisella pathogenicity. This methodology should be applicable to a variety of systems and other pathogens.

A uroguanylin-GUCY2C endocrine axis regulates feeding in mice.

Intestinal enteroendocrine cells are critical to central regulation of caloric consumption, since they activate hypothalamic circuits that decrease appetite and thereby restrict meal size by secreting hormones in response to nutrients in the gut. Although guanylyl cyclase and downstream cGMP are essential regulators of centrally regulated feeding behavior in invertebrates, the role of this primordial signaling mechanism in mammalian appetite regulation has eluded definition. In intestinal epithelial cells, guanylyl cyclase 2C (GUCY2C) is a transmembrane receptor that makes cGMP in response to the paracrine hormones guanylin and uroguanylin, which regulate epithelial cell dynamics along the crypt-villus axis. Here, we show that silencing of GUCY2C in mice disrupts satiation, resulting in hyperphagia and subsequent obesity and metabolic syndrome. This defined an appetite-regulating uroguanylin-GUCY2C endocrine axis, which we confirmed by showing that nutrient intake induces intestinal prouroguanylin secretion into the circulation. The prohormone signal is selectively decoded in the hypothalamus by proteolytic liberation of uroguanylin, inducing GUCY2C signaling and consequent activation of downstream anorexigenic pathways. Thus, evolutionary diversification of primitive guanylyl cyclase signaling pathways allows GUCY2C to coordinate endocrine regulation of central food acquisition pathways with paracrine control of intestinal homeostasis. Moreover, the uroguanylin-GUCY2C endocrine axis may provide a therapeutic target to control appetite, obesity, and metabolic syndrome.